# Magnetic field

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Magnetic field

## 2. B

### 2.1. a moving point charge

2.1.1. Biot-Savart Law

2.1.1.1. qv x r

### 2.2. current in wire of short length

2.2.1. .

2.2.1.1. long wire add up all the shorts r vector is (x, -y, 0)

2.2.1.2. conventional current

### 2.3. wire

2.3.1. derivation

2.4.1. solenoid

## 4. Retardation (Decay of electric and magnetic forces, when charge and motion of charge removed).

### 4.1. Does this indicate fields are real or is this only its relativistic nature?

4.1.1. Biotsavart law has no time reference, so it cannot be relativistically correct.

4.1.2. Only an approximation that is appropriated only when v << c

5.4.1. .

## 6. F

### 6.1. point charge

6.1.1. x. Determine the magnetic force on a moving-charge/current due to a magnetic field.

6.1.1.1. deflection law

6.1.1.1.1. v x B

6.1.2. x. Lorentz force

## 7. x. define electron current

### 7.1. electron current (electrons per second)

7.1.1. conventional current (Coulombs per sec. = Amperes)